From: Sebastian Ott <sebott@redhat.com>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-kernel@vger.kernel.org
Cc: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>
Subject: [PATCH 0/4] KVM: arm64: emulation for CTR_EL0
Date: Fri, 5 Apr 2024 14:01:04 +0200 [thread overview]
Message-ID: <20240405120108.11844-1-sebott@redhat.com> (raw)
Hej folks,
I'm looking into supporting migration between 2 Ampere Altra (Max)
machines (using Neoverse-N1). They are almost identical regarding
their feature id register state except for CTR_EL0.DIC which is set
on one machine but not the other.
CTR_EL0 is currently marked as invariant and migrating a VM between
those 2 machines using qemu fails.
I've send this out as an RFC before [0]. What I've changed here
based on feedback I've got from Marc was:
* store the emulated value per VM and not per VCPU
* allow to change more values than just the DIC bit
* only trap guest access to that reg when needed
* make sure to not present the guest with an inconsistent register set
Patch 2 adds a ctr_el0 member to struct kvm_arch - would it be preferred
to add it into kvm->arch.id_regs[] (this would mean to increase that
array 4x)?
Patch 3 resets CLIDR_EL1 after a write to CTR_EL0 potentially changing
the value for CLIDR_EL1 - would that be ok for userspace?
Thanks,
Sebastian
[0]: https://lore.kernel.org/all/20240318111636.10613-1-sebott@redhat.com/T/
Sebastian Ott (4):
KVM: arm64: change return value in arm64_check_features()
KVM: arm64: maintain per VM value for CTR_EL0
KVM: arm64: add emulation for CTR_EL0 register
KVM: arm64: show writable masks for feature registers
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/kvm/sys_regs.c | 131 ++++++++++++++++++++----------
2 files changed, 89 insertions(+), 43 deletions(-)
--
2.42.0
next reply other threads:[~2024-04-05 12:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-05 12:01 Sebastian Ott [this message]
2024-04-05 12:01 ` [PATCH 1/4] KVM: arm64: change return value in arm64_check_features() Sebastian Ott
2024-04-05 12:01 ` [PATCH 2/4] KVM: arm64: maintain per VM value for CTR_EL0 Sebastian Ott
2024-04-13 10:04 ` Marc Zyngier
2024-04-13 13:05 ` Sebastian Ott
2024-04-05 12:01 ` [PATCH 3/4] KVM: arm64: add emulation for CTR_EL0 register Sebastian Ott
2024-04-13 10:19 ` Marc Zyngier
2024-04-13 13:50 ` Sebastian Ott
2024-04-14 8:35 ` Marc Zyngier
2024-04-05 12:01 ` [PATCH 4/4] KVM: arm64: show writable masks for feature registers Sebastian Ott
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